[clang] [analyzer] Fix uninitialized base class with initializer list when ctor is not declared in the base class (#70464) (PR #70792)

[Balazs Benics via cfe-commits]

https://github.com/steakhal requested changes to this pull request.

I must admit that I didn't look at the issue too much, but this patch speaks for itself.
Clean, to the point, and meets our conventions. Kudos.
I only have minor remarks.

And be sure to mention `Fixes #70464` in the PR/commit message to auto-close the issue.

https://github.com/llvm/llvm-project/pull/70792